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2021 Vol. 39, No. 11
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2021, 39(11): 1-15,40.
doi: 10.13205/j.hjgc.202111001
Abstract:
Highly-efficient treatment of refractory industrial wastewater remains an important issue for economic development and environmental protection in China. This article reviews the domestic and overseas progresses of technologies and theories regarding the area within decades. By depicting the advances of the three-stage system consisting of pretreatment, biological treatment, and advanced treatment, the representative technologies with their applicability and developing trends are discussed. The interdisciplinary theoretical explorations in the identification of contaminant degradation pathways, microbial community analysis, and risk assessment of toxic substances are also comprehensively summarized. With the current strategy of promoting ecological civilization and low-carbon economy in China, the increasingly diversified and systematic wastewater treatment technologies and theories will profoundly influence the layout and paths of future industrial development.
Highly-efficient treatment of refractory industrial wastewater remains an important issue for economic development and environmental protection in China. This article reviews the domestic and overseas progresses of technologies and theories regarding the area within decades. By depicting the advances of the three-stage system consisting of pretreatment, biological treatment, and advanced treatment, the representative technologies with their applicability and developing trends are discussed. The interdisciplinary theoretical explorations in the identification of contaminant degradation pathways, microbial community analysis, and risk assessment of toxic substances are also comprehensively summarized. With the current strategy of promoting ecological civilization and low-carbon economy in China, the increasingly diversified and systematic wastewater treatment technologies and theories will profoundly influence the layout and paths of future industrial development.
2021, 39(11): 16-27,134.
doi: 10.13205/j.hjgc.202111002
Abstract:
The development and application of advanced treatment for industrial wastewater is current hotspot. In response to the challenge about the removal of non-biodegradable organics, this paper proposed an idea based on the identification of characteristic pollutants for developing and application of advanced treatment. According to this idea, the corresponding identification method and its application were summarized. As typical high-concentration refractory organics wastewater, coking wastewater, pharmaceutical wastewater, dye wastewater, and paper and pulp wastewater were summarized on the research progress of advanced treatment. Moreover, the successful application cases of advanced treatment of coking and pharmaceutical wastewater based on characteristic pollutant identification were presented. This review put forward suggestions on development direction of advanced treatment technology of industrial wastewater, and was helpful in providing technical support and scientific basis for the sustainable development of industry.
The development and application of advanced treatment for industrial wastewater is current hotspot. In response to the challenge about the removal of non-biodegradable organics, this paper proposed an idea based on the identification of characteristic pollutants for developing and application of advanced treatment. According to this idea, the corresponding identification method and its application were summarized. As typical high-concentration refractory organics wastewater, coking wastewater, pharmaceutical wastewater, dye wastewater, and paper and pulp wastewater were summarized on the research progress of advanced treatment. Moreover, the successful application cases of advanced treatment of coking and pharmaceutical wastewater based on characteristic pollutant identification were presented. This review put forward suggestions on development direction of advanced treatment technology of industrial wastewater, and was helpful in providing technical support and scientific basis for the sustainable development of industry.
2021, 39(11): 28-40.
doi: 10.13205/j.hjgc.202111003
Abstract:
The principles of sewage and wastewater generation as well as its influence on the aqueous solution properties of natural water body are established based on the perspectives of natural evolution and human activities. The rapid urbanization process as well as the careless agricultural and industrial management has brought along with increasingly serious surface water pollution, which at the micro-level, disturbs the centrifugal and centripetal migration balance of elements/compounds on the terrestrial surface. As a result, the water interface or hydrosphere becomes the hub for global material circulation. The numerous contradictions in the aquatic material circulation can be well resolved by the remarkable physical, chemical, physicochemical and biochemical functions hidden in water treatment techniques and principles. Therefore, the application of enantiomer technology between the properties of sewage/wastewater solution and the principles of treatment process constitutes a more holonomic and developable water industry. In addition, the proposed concept of aqueous solution properties also apply to the production and management of water supply and pure water. On account of the treatment of refractory and deleterious industrial organic wastewater such as coking wastewater, the common mission should be resource recovery, complementary utilization, and water recycling mechanism on the basis of the front-end process of cleaner production, featuring water treatment techniques with low energy/material consumptions, high removal efficiency of critical pollutants, as well as low carbon emission. Based on the change of the properties of aqueous solution and its process evolution, the technological theory and technical boundary of water pollution control will be widened. The aqueous industry combining water pollution control and water environment protection should strive for the simultaneous development in technology, economics and social purpose, dedicating to the response of green, low-carbon, recycling and other ecological goals, that is, life, production, and ecological of "trinity" coordinated development.
The principles of sewage and wastewater generation as well as its influence on the aqueous solution properties of natural water body are established based on the perspectives of natural evolution and human activities. The rapid urbanization process as well as the careless agricultural and industrial management has brought along with increasingly serious surface water pollution, which at the micro-level, disturbs the centrifugal and centripetal migration balance of elements/compounds on the terrestrial surface. As a result, the water interface or hydrosphere becomes the hub for global material circulation. The numerous contradictions in the aquatic material circulation can be well resolved by the remarkable physical, chemical, physicochemical and biochemical functions hidden in water treatment techniques and principles. Therefore, the application of enantiomer technology between the properties of sewage/wastewater solution and the principles of treatment process constitutes a more holonomic and developable water industry. In addition, the proposed concept of aqueous solution properties also apply to the production and management of water supply and pure water. On account of the treatment of refractory and deleterious industrial organic wastewater such as coking wastewater, the common mission should be resource recovery, complementary utilization, and water recycling mechanism on the basis of the front-end process of cleaner production, featuring water treatment techniques with low energy/material consumptions, high removal efficiency of critical pollutants, as well as low carbon emission. Based on the change of the properties of aqueous solution and its process evolution, the technological theory and technical boundary of water pollution control will be widened. The aqueous industry combining water pollution control and water environment protection should strive for the simultaneous development in technology, economics and social purpose, dedicating to the response of green, low-carbon, recycling and other ecological goals, that is, life, production, and ecological of "trinity" coordinated development.
2021, 39(11): 41-45,109.
doi: 10.13205/j.hjgc.202111004
Abstract:
This paper introduced the development status and environmental challenges of modern coal chemical industry, and analyzed the composition and characteristics of wastewater in modern coal chemical industry. Through the classification and collection, treatment and reuse for organic wastewater and salinity wastewater, the focus of the wastewater treatment system in modern coal chemical industry has evolved from unit technology to key technology integration considering process convergence and control from the source, forming the basic technical framework of Wastewater Pretreatment-Biological Treatment-Reuse of Reclaimed Wastewater-Membrane Treatment of Salinity Wastewater-Evaporative Crystallization Treatment. At the same time, the paper analyzed the problems in the actual operation of wastewater treatment system of modern coal chemical projects, put forward solutions and optimized the integration of the technologies, further broke through the technical bottleneck of near-zero discharge for wastewater in modern coal chemical industry, reduced the economic cost of near-zero discharge, and improved the stability of operation.
This paper introduced the development status and environmental challenges of modern coal chemical industry, and analyzed the composition and characteristics of wastewater in modern coal chemical industry. Through the classification and collection, treatment and reuse for organic wastewater and salinity wastewater, the focus of the wastewater treatment system in modern coal chemical industry has evolved from unit technology to key technology integration considering process convergence and control from the source, forming the basic technical framework of Wastewater Pretreatment-Biological Treatment-Reuse of Reclaimed Wastewater-Membrane Treatment of Salinity Wastewater-Evaporative Crystallization Treatment. At the same time, the paper analyzed the problems in the actual operation of wastewater treatment system of modern coal chemical projects, put forward solutions and optimized the integration of the technologies, further broke through the technical bottleneck of near-zero discharge for wastewater in modern coal chemical industry, reduced the economic cost of near-zero discharge, and improved the stability of operation.
2021, 39(11): 46-51.
doi: 10.13205/j.hjgc.202111005
Abstract:
Produced water containing polymer has the characteristics of complex water quality, high viscosity, high degree of emulsification, and high oil content, which causes difficulty in oil-water separation and has serious impacts on oilfield production operations and the environment. This study analyzed the water quality characteristics of the polymer-containing produced water, and summarized the treatment technologies of the polymer-containing produced water, such as membrane separation method, air flotation method, advanced oxidation method, microbial method, etc., and explained the application of these treatment processes in various oil fields. The advantages and problems of various treatment technologies were described. This study also introduced the treatment technologies of polymer-containing produced water and the development of skid-mounted integrated water treatment equipment. Finally, some prospects were put forward for future research of polymer-containing produced water treatment technology, hoping to provide reference for the researches and engineering application of the sewage treatment technology.
Produced water containing polymer has the characteristics of complex water quality, high viscosity, high degree of emulsification, and high oil content, which causes difficulty in oil-water separation and has serious impacts on oilfield production operations and the environment. This study analyzed the water quality characteristics of the polymer-containing produced water, and summarized the treatment technologies of the polymer-containing produced water, such as membrane separation method, air flotation method, advanced oxidation method, microbial method, etc., and explained the application of these treatment processes in various oil fields. The advantages and problems of various treatment technologies were described. This study also introduced the treatment technologies of polymer-containing produced water and the development of skid-mounted integrated water treatment equipment. Finally, some prospects were put forward for future research of polymer-containing produced water treatment technology, hoping to provide reference for the researches and engineering application of the sewage treatment technology.
2021, 39(11): 52-61.
doi: 10.13205/j.hjgc.202111006
Abstract:
Acid mine drainage (AMD), generated during the exploitation and utilization of mineral resources, has seriously impact on the surrounding ecological environment, especially on the water environment. The carbonate rocks from the karst region not only neutralize the acidity of AMD, but also remove the contaminants by oxidation and reduction, dissolution and precipitation, ligand exchange, adsorption and complexation and other mechanisms, as well as the sediments (goethite, schwertmannite, ferrihydrite, etc) from AMD's reaction with carbonate. This paper summarized the reaction mechanism between AMD and carbonate and the physical and chemical behaviors of carbonate dissolution under AMD action, and provided an overview of the types of secondary minerals formed in the process of AMD-carbonate interaction, the formation conditions, the order of formation and the environmental significance. Furthermore, it reviewed the research progress on the treatment methods of AMD by carbonate rocks, which could provide references for further improving continuous effectiveness of carbonate for treating different types of AMD, establishing the life prediction models of reaction system and optimizing the parameters of treatment methods for AMD.
Acid mine drainage (AMD), generated during the exploitation and utilization of mineral resources, has seriously impact on the surrounding ecological environment, especially on the water environment. The carbonate rocks from the karst region not only neutralize the acidity of AMD, but also remove the contaminants by oxidation and reduction, dissolution and precipitation, ligand exchange, adsorption and complexation and other mechanisms, as well as the sediments (goethite, schwertmannite, ferrihydrite, etc) from AMD's reaction with carbonate. This paper summarized the reaction mechanism between AMD and carbonate and the physical and chemical behaviors of carbonate dissolution under AMD action, and provided an overview of the types of secondary minerals formed in the process of AMD-carbonate interaction, the formation conditions, the order of formation and the environmental significance. Furthermore, it reviewed the research progress on the treatment methods of AMD by carbonate rocks, which could provide references for further improving continuous effectiveness of carbonate for treating different types of AMD, establishing the life prediction models of reaction system and optimizing the parameters of treatment methods for AMD.
2021, 39(11): 62-68,88.
doi: 10.13205/j.hjgc.202111007
Abstract:
It is more economical and sustainable that using biological removal method to treat selenium pollution in water bodies. However, most selenate-reducing model bacteria strains have poor environmental adaptability and are difficult in engineering applications. Using certain denitrifying bacteria with selenate reducing ability to treat selenium pollution is a new attempt. This study focused on the selenate-reducing flora dominated by denitrifying bacteria, by using the comparative analysis of substrate reduction rate, combined with the microbial community analysis and functional gene quantification. And we confirmed that periplasmic (Nap) nitrate reductase dominated the selenite reduction, clarified the role of denitrifying bacteria in the selenate reduction process, and further enriched the selenium-reducing flora. Furthermore, we proposed a new selenate removal strategy, that was, enriching the selenate-reducing activated sludge using nitrate as electron acceptor, greatly increased the selenate reduction efficiency and was conducive to engineering application.
It is more economical and sustainable that using biological removal method to treat selenium pollution in water bodies. However, most selenate-reducing model bacteria strains have poor environmental adaptability and are difficult in engineering applications. Using certain denitrifying bacteria with selenate reducing ability to treat selenium pollution is a new attempt. This study focused on the selenate-reducing flora dominated by denitrifying bacteria, by using the comparative analysis of substrate reduction rate, combined with the microbial community analysis and functional gene quantification. And we confirmed that periplasmic (Nap) nitrate reductase dominated the selenite reduction, clarified the role of denitrifying bacteria in the selenate reduction process, and further enriched the selenium-reducing flora. Furthermore, we proposed a new selenate removal strategy, that was, enriching the selenate-reducing activated sludge using nitrate as electron acceptor, greatly increased the selenate reduction efficiency and was conducive to engineering application.
2021, 39(11): 69-76.
doi: 10.13205/j.hjgc.202111008
Abstract:
In this study, the changes of biological toxicity during the ozonation of phenol, m-cresol, o-cresol and m-dihydroxybenzene were investigated, and the fluorescence spectra of highly toxic intermediates were revealed. It was found that the biological toxicity of four phenolic compounds firstly increased and then decreased after ozonation with the reaction time passed. The maximum biological toxicity of phenol, m-cresol, o-cresol and m-dihydroxybenzene was 16.7, 26.3, 34.8, 3.2 times of their initial toxicity, respectively. At the toxicity peaks, the toxic unit were removed by 95.2%, 94.5%, 87.3% and 44.4% respectively, after adding Na2SO3, and there was a significant correlation between the change of toxic unit and the recovery of fluorescence intensity peak at emission wavelength of 295~305 nm (P<0.05). It was speculated that the highly toxic intermediates formed during the ozonation of phenols were mainly oxidative carbonyl compounds. This study could provide new insight into the construction of rapid quantitative characterization of biological toxicity after ozonation based on the optical characteristics.
In this study, the changes of biological toxicity during the ozonation of phenol, m-cresol, o-cresol and m-dihydroxybenzene were investigated, and the fluorescence spectra of highly toxic intermediates were revealed. It was found that the biological toxicity of four phenolic compounds firstly increased and then decreased after ozonation with the reaction time passed. The maximum biological toxicity of phenol, m-cresol, o-cresol and m-dihydroxybenzene was 16.7, 26.3, 34.8, 3.2 times of their initial toxicity, respectively. At the toxicity peaks, the toxic unit were removed by 95.2%, 94.5%, 87.3% and 44.4% respectively, after adding Na2SO3, and there was a significant correlation between the change of toxic unit and the recovery of fluorescence intensity peak at emission wavelength of 295~305 nm (P<0.05). It was speculated that the highly toxic intermediates formed during the ozonation of phenols were mainly oxidative carbonyl compounds. This study could provide new insight into the construction of rapid quantitative characterization of biological toxicity after ozonation based on the optical characteristics.
2021, 39(11): 77-82,118.
doi: 10.13205/j.hjgc.202111009
Abstract:
The aim of this study was to enhance the typical refractory organics degradation in the wastewater treatment by using A Fenton-like catalyst, which was synthesized and tested for the antipyrine and dyes degradation. The results demonstrated that the metallic oxide catalyst, Cu1-xCoxFe2O4 prepared by the hydrothermal method had a good crystal structure with the specific surface area of 147.3~187.5 m2/g, and the saturation magnetization value of 17.2~62.3 EMU/g. With the Co content increasing, the catalytic activity of the catalysts increased significantly. The optimized catalyst of Cu0.25Co0.75Fe2O4 had the applicable pH range of 7~9. With the initial antipyrine concentration of 50 mg/L, the catalyst dosage of 0.7 g/L and H2O2 dosage of 150 mmol/L, the antipyrine removal reached 93.1% at the initial pH=7 and 94.7% at the initial pH=9, respectively. Different types of refractory organic compounds, such as rhodamine B and acid orange Ⅱ, could also be effectively degraded with the catalyst. After 5 cycles of magnetic recovery and reuse of the catalyst, the antipyrine removal could be kept 80% above, indicating that the catalyst had good stability and reusability. The Fenton-like catalyst synthesized in this study provided scientific basis for efficient removal of refractory organic compounds from wastewater.
The aim of this study was to enhance the typical refractory organics degradation in the wastewater treatment by using A Fenton-like catalyst, which was synthesized and tested for the antipyrine and dyes degradation. The results demonstrated that the metallic oxide catalyst, Cu1-xCoxFe2O4 prepared by the hydrothermal method had a good crystal structure with the specific surface area of 147.3~187.5 m2/g, and the saturation magnetization value of 17.2~62.3 EMU/g. With the Co content increasing, the catalytic activity of the catalysts increased significantly. The optimized catalyst of Cu0.25Co0.75Fe2O4 had the applicable pH range of 7~9. With the initial antipyrine concentration of 50 mg/L, the catalyst dosage of 0.7 g/L and H2O2 dosage of 150 mmol/L, the antipyrine removal reached 93.1% at the initial pH=7 and 94.7% at the initial pH=9, respectively. Different types of refractory organic compounds, such as rhodamine B and acid orange Ⅱ, could also be effectively degraded with the catalyst. After 5 cycles of magnetic recovery and reuse of the catalyst, the antipyrine removal could be kept 80% above, indicating that the catalyst had good stability and reusability. The Fenton-like catalyst synthesized in this study provided scientific basis for efficient removal of refractory organic compounds from wastewater.
2021, 39(11): 83-88.
doi: 10.13205/j.hjgc.202111010
Abstract:
2,4,6-trichlorophenol (TCP) is a recalcitrant organic compound, and reductive dechlorination is the key step for biodegradation of TCP, which is usually carried out in anaerobic conditions. Chloride ion in the para-position of TCP is harder to remove compared to Cl in the ortho-position, which means that 4-chlorophenol (4-CP), an intermediate of TCP reductive dechlorination, is difficult to further biodegrade in anaerobic conditions. However, the 4-CP was effectively biodegraded when the anaerobic mode was switched into an aerobic mode. Based on this advantage of alternating between anaerobic and aerobic modes, a vertical baffled bioreactor (VBBR) was employed for TCP biodegradation. Compared with anaerobic biodegradation alone, alternating between anaerobic and aerobic modes significantly enhanced TCP biodegradation. For an initial TCP concentration of 50 μmol/L, the time for complete removal of TCP was shortened from 34 h to less than 12 h. The mechanism was the relief of inhibitions by TCP-biodegradation intermediates. For example, phenol, an intermediate of 4-CP reductive dechlorination, got more rapid biodegradation in the aerobic mode, which relieved its inhibition and enhanced the biodegradation of TCP in the anaerobic mode.
2,4,6-trichlorophenol (TCP) is a recalcitrant organic compound, and reductive dechlorination is the key step for biodegradation of TCP, which is usually carried out in anaerobic conditions. Chloride ion in the para-position of TCP is harder to remove compared to Cl in the ortho-position, which means that 4-chlorophenol (4-CP), an intermediate of TCP reductive dechlorination, is difficult to further biodegrade in anaerobic conditions. However, the 4-CP was effectively biodegraded when the anaerobic mode was switched into an aerobic mode. Based on this advantage of alternating between anaerobic and aerobic modes, a vertical baffled bioreactor (VBBR) was employed for TCP biodegradation. Compared with anaerobic biodegradation alone, alternating between anaerobic and aerobic modes significantly enhanced TCP biodegradation. For an initial TCP concentration of 50 μmol/L, the time for complete removal of TCP was shortened from 34 h to less than 12 h. The mechanism was the relief of inhibitions by TCP-biodegradation intermediates. For example, phenol, an intermediate of 4-CP reductive dechlorination, got more rapid biodegradation in the aerobic mode, which relieved its inhibition and enhanced the biodegradation of TCP in the anaerobic mode.
2021, 39(11): 89-95.
doi: 10.13205/j.hjgc.202111011
Abstract:
In the present work, a bipolar membrane electrodialysis(BMED) was used to remove and recover hexavalent chromium[Cr(Ⅵ)] in form of H2CrO4 from the simulated wastewater. The effects of electrolyte concentration in wastewater, current density, and initial Cr(Ⅵ) concentration on removal of Cr(Ⅵ) were investigated. The experimental results showed that the electrolyte concentration of 1 g/L and current density of 2 mA/cm2 were the optimal experimental conditions when initial Cr(Ⅵ) concentration was 500 mg/L, and the removal rate was 97.6%. A higher current efficiency (CE) and a lower specific energy consumption (SEC) were obtained when two and three wastewater compartment were equipped in the BMED system and Cr(Ⅵ) removal rates in all wastewater compartments were higher than 97.0%. With the increase in the number of equipped wastewater compartment from one to two and three in the BMED system, CE increased from 31.5% to 125.8% and 284.4%, SEC decreased from 19.49×10-3 to 7.76×10-3, 4.17×10-3 kW·h/g Cr(Ⅵ), respectively. Experimental results showed that the BMED was an effective method for the removal and recovery of Cr(Ⅵ) from aqueous solution.
In the present work, a bipolar membrane electrodialysis(BMED) was used to remove and recover hexavalent chromium[Cr(Ⅵ)] in form of H2CrO4 from the simulated wastewater. The effects of electrolyte concentration in wastewater, current density, and initial Cr(Ⅵ) concentration on removal of Cr(Ⅵ) were investigated. The experimental results showed that the electrolyte concentration of 1 g/L and current density of 2 mA/cm2 were the optimal experimental conditions when initial Cr(Ⅵ) concentration was 500 mg/L, and the removal rate was 97.6%. A higher current efficiency (CE) and a lower specific energy consumption (SEC) were obtained when two and three wastewater compartment were equipped in the BMED system and Cr(Ⅵ) removal rates in all wastewater compartments were higher than 97.0%. With the increase in the number of equipped wastewater compartment from one to two and three in the BMED system, CE increased from 31.5% to 125.8% and 284.4%, SEC decreased from 19.49×10-3 to 7.76×10-3, 4.17×10-3 kW·h/g Cr(Ⅵ), respectively. Experimental results showed that the BMED was an effective method for the removal and recovery of Cr(Ⅵ) from aqueous solution.
EFFECT OF PYROLYSIS TEMPERATURE ON THE PHYSICAL AND CHEMICAL CHARACTERISTICS OF BAMBOO-BASED BIOCHAR
2021, 39(11): 96-102,126.
doi: 10.13205/j.hjgc.202111012
Abstract:
As a new environmental functional material, biochar showed application prospects in environmental pollution remediation, soil improvement, greenhouse gas emission reduction, and enhanced biological nitrogen removal from wastewater. Biochars were prepared from bamboo powder at different pyrolysis temperatures, and their electron exchange capacity, surface functional groups, and elemental composition were characterized to explore the effect of pyrolysis temperatures on the physicochemical characteristics of bamboo-based biochar. The results showed that while the pyrolysis temperature increased from 300℃ to 700℃, the electron donating capacity (EDC) of biochars generally increased first and then decreased. The highest EDC was obtained in the biochars prepared at 300℃ and 400℃ with the value of 0.33 e-/g Biochar and 0.35 e-/g Biochar, respectively, had higher potential in improving biological nitrogen removal; and the lowest EDC was obtained in the biochars prepared at 600℃ with the value of 0.07 e-/g Biochar. Accordingly, the average oxidation degree Cox calculated from the elemental content was corresponding to the results of EDC. With the increase of pyrolysis temperature, the Cox of biochars changed from negative to positive. When the pyrolysis temperature was 300℃ or 400℃, the Cox of the biochars was negative, indicating that the biochars was more reductive and less oxidizable than those prepared at 500~700℃, i.e., higher electron donating capacity (EDC) and lower electron accepting capacity (EAC). In addition, Fourier transform infrared spectroscopy showed that the hydroxyl content of the biochars was highest at 300℃ and 400℃, which was consistent with their highest EDC.
As a new environmental functional material, biochar showed application prospects in environmental pollution remediation, soil improvement, greenhouse gas emission reduction, and enhanced biological nitrogen removal from wastewater. Biochars were prepared from bamboo powder at different pyrolysis temperatures, and their electron exchange capacity, surface functional groups, and elemental composition were characterized to explore the effect of pyrolysis temperatures on the physicochemical characteristics of bamboo-based biochar. The results showed that while the pyrolysis temperature increased from 300℃ to 700℃, the electron donating capacity (EDC) of biochars generally increased first and then decreased. The highest EDC was obtained in the biochars prepared at 300℃ and 400℃ with the value of 0.33 e-/g Biochar and 0.35 e-/g Biochar, respectively, had higher potential in improving biological nitrogen removal; and the lowest EDC was obtained in the biochars prepared at 600℃ with the value of 0.07 e-/g Biochar. Accordingly, the average oxidation degree Cox calculated from the elemental content was corresponding to the results of EDC. With the increase of pyrolysis temperature, the Cox of biochars changed from negative to positive. When the pyrolysis temperature was 300℃ or 400℃, the Cox of the biochars was negative, indicating that the biochars was more reductive and less oxidizable than those prepared at 500~700℃, i.e., higher electron donating capacity (EDC) and lower electron accepting capacity (EAC). In addition, Fourier transform infrared spectroscopy showed that the hydroxyl content of the biochars was highest at 300℃ and 400℃, which was consistent with their highest EDC.
2021, 39(11): 103-109.
doi: 10.13205/j.hjgc.202111013
Abstract:
This study adopted pyrolysis to prepare biochar from pharmaceutical sludge, investigated the influence of ZnCl2 activation conditions on the adsorption performance of biochar, and explored its performance in pharmaceutical wastewater treatment. Increasing the concentration and impregnation ratio of ZnCl2 activator improved the adsorption performance of pharmaceutical sludge biochar. The specific surface area of biochar reached 534.91 m2/g, and iodine value and phenol adsorption value reached 674.61 mg/g and 119.12 mg/g, respectively, under ZnCl2 concentration of 5 mol/L and impregnation ratio of 1:1. The adsorption kinetics of COD in pharmaceutical wastewater by the pharmaceutical sludge biochar was more consistent with the Elovich model and the pseudo-second order model. The rapid adsorption of COD by the biochar occurred within 1 h. The increase in the dosage of biochar improved the removal of pollutants in wastewater. COD removal and AOX removal achieved 66.3% and 61.8%, respectively, by adsorption at 50 g/L biochar dosage for 1 h. The multi-stage adsorption could achieve better pollutant removal effect at a lower dosage, as the 6-stage adsorption at a biochar dosage of 1 g/L removed 72.8% of COD and 65.2% of AOX. The study revealed that pyrolysis of pharmaceutical sludge with ZnCl2 activation could produce high quality biochar, which possessed excellent potential in pharmaceutical wastewater adsorption treatment.
This study adopted pyrolysis to prepare biochar from pharmaceutical sludge, investigated the influence of ZnCl2 activation conditions on the adsorption performance of biochar, and explored its performance in pharmaceutical wastewater treatment. Increasing the concentration and impregnation ratio of ZnCl2 activator improved the adsorption performance of pharmaceutical sludge biochar. The specific surface area of biochar reached 534.91 m2/g, and iodine value and phenol adsorption value reached 674.61 mg/g and 119.12 mg/g, respectively, under ZnCl2 concentration of 5 mol/L and impregnation ratio of 1:1. The adsorption kinetics of COD in pharmaceutical wastewater by the pharmaceutical sludge biochar was more consistent with the Elovich model and the pseudo-second order model. The rapid adsorption of COD by the biochar occurred within 1 h. The increase in the dosage of biochar improved the removal of pollutants in wastewater. COD removal and AOX removal achieved 66.3% and 61.8%, respectively, by adsorption at 50 g/L biochar dosage for 1 h. The multi-stage adsorption could achieve better pollutant removal effect at a lower dosage, as the 6-stage adsorption at a biochar dosage of 1 g/L removed 72.8% of COD and 65.2% of AOX. The study revealed that pyrolysis of pharmaceutical sludge with ZnCl2 activation could produce high quality biochar, which possessed excellent potential in pharmaceutical wastewater adsorption treatment.
2021, 39(11): 110-118.
doi: 10.13205/j.hjgc.202111014
Abstract:
Leachate from municipal solid waste incineration plants is a kind of refractory wastewater with a high concentration of ammonia nitrogen and organic matter. Multi-stage nitrification and denitrification process is often used for biological denitrification of leachate, which has the disadvantages of high energy consumption and low efficiency. In this study, a continuous flow three-stage process of anaerobic digestion-partial nitrification-anammox was establish to treat the leachate with the anammox process as the key technology, and its biological denitrification effect, changes of organic matters, functional microbial activity and composition analysis of leachate from waste incineration plant were investigated. The results showed that when the influent NH4+-N and COD concentrations were 900~1800 mg/L and 3000~20000 mg/L, respectively, and the total inorganic nitrogen (TIN) and COD removal efficiency reached 85% and 77%, respectively. Specifically, the COD removal efficiency was about 45% in the anaerobic digestion reactor. The accumulation rate of NO2--N in the partial nitrification reactor remained 97% above, and the removal efficiency of total inorganic nitrogen was about 85% in the Anammox reactor; heterotrophic denitrification also had occurred in the system. The activity of ammonia oxidizing bacteria and anammox bacteria in the autotrophic nitrogen removal system decreased in varying degrees after the leachate added. The results of metagenomics combined with 16S rDNA high-throughput sequencing analysis showed that the relative abundance of heterotrophic denitrifiers in the partial nitrification and Anammox reactors increased, due to the high concentration of organic matters in the leachate. Specially, Anammox was inhibited by refractory organics, among which Candidatus_Kuenenia was adaptable. Nevertheless, after a long-term acclimation, the anammox bacteria could still maintain a high nitrogen removal efficiency.
Leachate from municipal solid waste incineration plants is a kind of refractory wastewater with a high concentration of ammonia nitrogen and organic matter. Multi-stage nitrification and denitrification process is often used for biological denitrification of leachate, which has the disadvantages of high energy consumption and low efficiency. In this study, a continuous flow three-stage process of anaerobic digestion-partial nitrification-anammox was establish to treat the leachate with the anammox process as the key technology, and its biological denitrification effect, changes of organic matters, functional microbial activity and composition analysis of leachate from waste incineration plant were investigated. The results showed that when the influent NH4+-N and COD concentrations were 900~1800 mg/L and 3000~20000 mg/L, respectively, and the total inorganic nitrogen (TIN) and COD removal efficiency reached 85% and 77%, respectively. Specifically, the COD removal efficiency was about 45% in the anaerobic digestion reactor. The accumulation rate of NO2--N in the partial nitrification reactor remained 97% above, and the removal efficiency of total inorganic nitrogen was about 85% in the Anammox reactor; heterotrophic denitrification also had occurred in the system. The activity of ammonia oxidizing bacteria and anammox bacteria in the autotrophic nitrogen removal system decreased in varying degrees after the leachate added. The results of metagenomics combined with 16S rDNA high-throughput sequencing analysis showed that the relative abundance of heterotrophic denitrifiers in the partial nitrification and Anammox reactors increased, due to the high concentration of organic matters in the leachate. Specially, Anammox was inhibited by refractory organics, among which Candidatus_Kuenenia was adaptable. Nevertheless, after a long-term acclimation, the anammox bacteria could still maintain a high nitrogen removal efficiency.
2021, 39(11): 119-126.
doi: 10.13205/j.hjgc.202111015
Abstract:
MnOx/GAC catalyst was prepared by acid-thermal oxidation modification method loading manganese oxide on activated carbon, and the performance of its catalytic oxidation degrading o-chlorophenol was studied. Results showed that when the catalyst dosage was 0.1 g/L, the ozone concentration was 20 mg/L, the gas flow was 0.5 L/min, and the initial pH was 6, the TOC removal rate of o-chlorophenol reached 95% after 120 min, which was 55% higher than ozonation alone. The reaction rate and TOC removal rate was greater when increasing ozone concentration and gas flow within a certain range, since excessive ozone might lower the TOC removal rate. Effects of different ions on TOC removal rate was studied. No significant difference was noticed on TOC removal rate with the addition of 1 mmol/L NO3-, SO42-, Cl-, separately. TOC removal was decreased 10% with the addition of 1 mmol/L Br-. pH was an important factor affecting the oxidation capacity of the system. Under acidic conditions, TOC removal rate was much higher than in alkaline conditions, which might be related to the behavior of the catalyst surface functional group and the accumulation of inorganic carbon in the system. In addition, the relationship between the form of surface hydroxyl groups on the catalyst and pH was proposed, and the formation pathways of active species under different circumstances were speculated.
MnOx/GAC catalyst was prepared by acid-thermal oxidation modification method loading manganese oxide on activated carbon, and the performance of its catalytic oxidation degrading o-chlorophenol was studied. Results showed that when the catalyst dosage was 0.1 g/L, the ozone concentration was 20 mg/L, the gas flow was 0.5 L/min, and the initial pH was 6, the TOC removal rate of o-chlorophenol reached 95% after 120 min, which was 55% higher than ozonation alone. The reaction rate and TOC removal rate was greater when increasing ozone concentration and gas flow within a certain range, since excessive ozone might lower the TOC removal rate. Effects of different ions on TOC removal rate was studied. No significant difference was noticed on TOC removal rate with the addition of 1 mmol/L NO3-, SO42-, Cl-, separately. TOC removal was decreased 10% with the addition of 1 mmol/L Br-. pH was an important factor affecting the oxidation capacity of the system. Under acidic conditions, TOC removal rate was much higher than in alkaline conditions, which might be related to the behavior of the catalyst surface functional group and the accumulation of inorganic carbon in the system. In addition, the relationship between the form of surface hydroxyl groups on the catalyst and pH was proposed, and the formation pathways of active species under different circumstances were speculated.
2021, 39(11): 127-134.
doi: 10.13205/j.hjgc.202111016
Abstract:
The aim of this study is to explore the electricity generation properties in the single-chamber air-cathode microbial fuel cell (MFC) with corn cob acid pyrolysis solution as the substrate. The optimized conditions for the pretreatment of corn cob with oxalic acid pyrolysis were as follows:reaction temperature of 160℃, reaction time of 90 min, oxalic acid dosage of 2% (by mass percentage). Under the optimized condition, the concentration of reducing sugar was 0.44 g/g corn cob and the solid digestibility was about 58%. Fed by the 20 times diluted solution of acid pyrolysis, the MFC could produce the maximum power density of 278 mW/m2. The period of electricity generation in the MFC was about 120 h. The COD removal rate in the MFC fed by different concentrations of corn cob acid pyrolysis solution reached more than 90.0%. With the decrease of the diluted factor, the coulombic efficiency (CE) of MFC decreased from 18.6% to 9.72%. Under different concentrations of corn cob hydrolysate, the highest relative abundance of Geobacter, a typical electrically active bacteria (EAB), was 3.40% in the bacterial community in the anodic biofilm of MFC at the genus level. The relative abundance of Klebsiella reached 41.6% under 20 times diluted corn cob acid pyrolysis solution. The results provided a scientific basis for the effective utilization of corn cob in MFC.
The aim of this study is to explore the electricity generation properties in the single-chamber air-cathode microbial fuel cell (MFC) with corn cob acid pyrolysis solution as the substrate. The optimized conditions for the pretreatment of corn cob with oxalic acid pyrolysis were as follows:reaction temperature of 160℃, reaction time of 90 min, oxalic acid dosage of 2% (by mass percentage). Under the optimized condition, the concentration of reducing sugar was 0.44 g/g corn cob and the solid digestibility was about 58%. Fed by the 20 times diluted solution of acid pyrolysis, the MFC could produce the maximum power density of 278 mW/m2. The period of electricity generation in the MFC was about 120 h. The COD removal rate in the MFC fed by different concentrations of corn cob acid pyrolysis solution reached more than 90.0%. With the decrease of the diluted factor, the coulombic efficiency (CE) of MFC decreased from 18.6% to 9.72%. Under different concentrations of corn cob hydrolysate, the highest relative abundance of Geobacter, a typical electrically active bacteria (EAB), was 3.40% in the bacterial community in the anodic biofilm of MFC at the genus level. The relative abundance of Klebsiella reached 41.6% under 20 times diluted corn cob acid pyrolysis solution. The results provided a scientific basis for the effective utilization of corn cob in MFC.
2021, 39(11): 135-142,178.
doi: 10.13205/j.hjgc.202111017
Abstract:
To explore and optimize the experimental conditions and influence factors of the removal of organic pollutants by persulfate activated with iron modified biochar prepared by the dipping-pyrolysis process, 2,4-dinitrotoluene (2,4-DNT) was selected as the target pollutant to investigate the effects of pyrolysis parameters (pyrolysis temperature, heating rate, and residence time), FeCl3 concentration and initial pH values on 2,4-DNT removal. The electron spin resonance and free radical quenching test were used to assess the intensity of SO4-· and ·OH in the PS/MBC system. The results showed that:1) The pyrolysis temperature had the most significant influence on removal of 2,4-DNT by PS activated with MBC, followed by heating rate and residence time. When the pyrolysis parameters were retained at 300℃, 3 h, and 10℃/min, the best removal of 2,4-DNT was obtained by PS/MBC oxidation. 2) The concentration of FeCl3 was an important factor of MBC activation. The removal of 2,4-DNT first increased and then decreased with the increase of the FeCl3 concentration. When the concentration of FeCl3 was retained at 100 mmol/L, the removal efficiency of 2,4-DNT reached 100% after the reaction of 5 h, and the pseudo-first-order kinetic constant (kobs) of 2,4-DNT removal was determined to be 1.373 min-1. 3)When the initial pH ranged from 5.0 to 9.0, 2,4-DNT had a good removal by PS/MBC oxidation, the removal efficiencies were 94.5%~83.6%, and the kobs values were 0.606~0.345 min-1. 4) ·OH was the main factor for the removal of 2,4-DNT by PS/MBC oxidation. The signals of ·OH with different strengths were observed, with the addition of MBC prepared by different pyrolysis temperatures and FeCl3 concentrations. The results showed that MBC prepared by dipping-pyrolysis could effectively activate PS to achieve the removal of organic pollutants, which provided a new idea for treatment of organically polluted water by PS based-advanced chemical oxidation.
To explore and optimize the experimental conditions and influence factors of the removal of organic pollutants by persulfate activated with iron modified biochar prepared by the dipping-pyrolysis process, 2,4-dinitrotoluene (2,4-DNT) was selected as the target pollutant to investigate the effects of pyrolysis parameters (pyrolysis temperature, heating rate, and residence time), FeCl3 concentration and initial pH values on 2,4-DNT removal. The electron spin resonance and free radical quenching test were used to assess the intensity of SO4-· and ·OH in the PS/MBC system. The results showed that:1) The pyrolysis temperature had the most significant influence on removal of 2,4-DNT by PS activated with MBC, followed by heating rate and residence time. When the pyrolysis parameters were retained at 300℃, 3 h, and 10℃/min, the best removal of 2,4-DNT was obtained by PS/MBC oxidation. 2) The concentration of FeCl3 was an important factor of MBC activation. The removal of 2,4-DNT first increased and then decreased with the increase of the FeCl3 concentration. When the concentration of FeCl3 was retained at 100 mmol/L, the removal efficiency of 2,4-DNT reached 100% after the reaction of 5 h, and the pseudo-first-order kinetic constant (kobs) of 2,4-DNT removal was determined to be 1.373 min-1. 3)When the initial pH ranged from 5.0 to 9.0, 2,4-DNT had a good removal by PS/MBC oxidation, the removal efficiencies were 94.5%~83.6%, and the kobs values were 0.606~0.345 min-1. 4) ·OH was the main factor for the removal of 2,4-DNT by PS/MBC oxidation. The signals of ·OH with different strengths were observed, with the addition of MBC prepared by different pyrolysis temperatures and FeCl3 concentrations. The results showed that MBC prepared by dipping-pyrolysis could effectively activate PS to achieve the removal of organic pollutants, which provided a new idea for treatment of organically polluted water by PS based-advanced chemical oxidation.
2021, 39(11): 143-148.
doi: 10.13205/j.hjgc.202111018
Abstract:
Adsorption and electrolysis are two effective methods to remove organics in water. In order to exert the synergistic effect of adsorption and electrolysis on organics, graphene oxide (RGO) with excellent adsorption conductivity and activated carbon (AC) were compounded to obtain composite materials, which were adhered to Ti electrode plate to obtain RGO/AC/Ti composite electrode for the electrolysis of methyl orange in water. The composite and electrode were characterized by SEM, FT-IR, BET, XRD, C-V and EIS. The electrochemical properties of Ti, RGO/Ti and RGO/AC/Ti for methyl orange were investigated. Compared with RGO, the specific surface area of RGO/AC increased from 318.1 m2/g to 405.1 m2/g. Compared with RGO/Ti, the specific capacitance of RGO/AC/Ti electrode decreased slightly, but the capacitance retention increased. When the electrolyte concentration was 0.15 mol/L, the electrode distance was 15 mm, the current was 100 mA and the pH was 6, the removal rates of methyl orange by Ti, RGO/Ti and RGO/AC/Ti electrodes were 48.1%, 79.5% and 88.8%, respectively. Then satisfactory removal effect was obtained. The paper provided a new idea for the treatment of refractory organic wastewater such as dyes.
Adsorption and electrolysis are two effective methods to remove organics in water. In order to exert the synergistic effect of adsorption and electrolysis on organics, graphene oxide (RGO) with excellent adsorption conductivity and activated carbon (AC) were compounded to obtain composite materials, which were adhered to Ti electrode plate to obtain RGO/AC/Ti composite electrode for the electrolysis of methyl orange in water. The composite and electrode were characterized by SEM, FT-IR, BET, XRD, C-V and EIS. The electrochemical properties of Ti, RGO/Ti and RGO/AC/Ti for methyl orange were investigated. Compared with RGO, the specific surface area of RGO/AC increased from 318.1 m2/g to 405.1 m2/g. Compared with RGO/Ti, the specific capacitance of RGO/AC/Ti electrode decreased slightly, but the capacitance retention increased. When the electrolyte concentration was 0.15 mol/L, the electrode distance was 15 mm, the current was 100 mA and the pH was 6, the removal rates of methyl orange by Ti, RGO/Ti and RGO/AC/Ti electrodes were 48.1%, 79.5% and 88.8%, respectively. Then satisfactory removal effect was obtained. The paper provided a new idea for the treatment of refractory organic wastewater such as dyes.
2021, 39(11): 149-153,158.
doi: 10.13205/j.hjgc.202111019
Abstract:
In view of the characteristics of printing and dyeing wastewater containing refractory organic matters, it is difficult to meet the discharge standard only through biochemical treatment. The wastewater was first subjected to biochemical treatment, an MBR system, and then Fenton catalytic oxidation process was used to treat the Membrane Bio-Reactor (MBR) effluent. The results showed that when the hydraulic retention time (HRT) of biochemical phase was 22 hours, the average COD of the MBR effluent was 100.3 mg/L; the effluent ammonia nitrogen, total nitrogen and total phosphorus all reached the first level A standard listed in GB 18918-2002. Under the conditions of MBR effluent pH=3, hydrogen peroxide dosage of 200 mg/L, ferrous sulfate dosage of 200 mg/L and reaction HRT of 2 hours,the COD of the effluent from the Fenton catalytic oxidation process was 28.1 mg/L, the chromaticity was 10.8 times and the operation cost was RMB 1.01/t. The three-dimensional fluorescence analysis of the inlet and outlet water showed that the wastewater contained aromatic protein like substances which were difficult to be biodegraded, but they could still be effectively decomposed after Fenton catalytic oxidation. From the perspective of treatment effect and treatment cost, the combined process of biochemical treatment and Fenton catalytic oxidation was suitable for printing and dyeing wastewater, which provided a certain reference for further engineering application.
In view of the characteristics of printing and dyeing wastewater containing refractory organic matters, it is difficult to meet the discharge standard only through biochemical treatment. The wastewater was first subjected to biochemical treatment, an MBR system, and then Fenton catalytic oxidation process was used to treat the Membrane Bio-Reactor (MBR) effluent. The results showed that when the hydraulic retention time (HRT) of biochemical phase was 22 hours, the average COD of the MBR effluent was 100.3 mg/L; the effluent ammonia nitrogen, total nitrogen and total phosphorus all reached the first level A standard listed in GB 18918-2002. Under the conditions of MBR effluent pH=3, hydrogen peroxide dosage of 200 mg/L, ferrous sulfate dosage of 200 mg/L and reaction HRT of 2 hours,the COD of the effluent from the Fenton catalytic oxidation process was 28.1 mg/L, the chromaticity was 10.8 times and the operation cost was RMB 1.01/t. The three-dimensional fluorescence analysis of the inlet and outlet water showed that the wastewater contained aromatic protein like substances which were difficult to be biodegraded, but they could still be effectively decomposed after Fenton catalytic oxidation. From the perspective of treatment effect and treatment cost, the combined process of biochemical treatment and Fenton catalytic oxidation was suitable for printing and dyeing wastewater, which provided a certain reference for further engineering application.
2021, 39(11): 154-158.
doi: 10.13205/j.hjgc.202111020
Abstract:
Taking the secondary pressure filtration water from a titanium dioxide plant in Shandong as the research object, the catalytic ozonation process and the treatment of titanium dioxide wastewater were investigated through a self-designed pilot plant, and the best experimental conditions for catalytic ozonation process were determined as follows:at room temperature, the catalytic ozone oxidation reaction time was 60 min, and the ozone concentration was 125 mg/L. The original NaClO process was also optimized, and the best process after optimization was as follows:NaClO dosage was 1.2%, and the reaction time was 30 minutes. When the average influent COD and ammonia nitrogen were 109.7 mg/L and 12.8 mg/L, the average effluent COD and ammonia nitrogen of the catalytic ozone process were 43.5 mg/L and 3.8 mg/L, respectively, and the average removal rates were 60% and 70.4%, respectively; and the average effluent COD and ammonia nitrogen in the NaClO process were 49.8 mg/L and 4.7 mg/L, respectively, and the average removal rates were 54.5% and 63.1%, respectively. Within 30 days, the standard-meeting rate of the catalytic ozonation process effluent was 100%, and that of the NaClO process effluent was 26.7%; the running cost of catalytic ozonation ton water treatment was RMB 1.12/t, and that of the NaClO treatment was RMB 12/t. The catalytic ozonation process was more suitable for treating titanium dioxide wastewater, compared with The NaClO oxidation process.
Taking the secondary pressure filtration water from a titanium dioxide plant in Shandong as the research object, the catalytic ozonation process and the treatment of titanium dioxide wastewater were investigated through a self-designed pilot plant, and the best experimental conditions for catalytic ozonation process were determined as follows:at room temperature, the catalytic ozone oxidation reaction time was 60 min, and the ozone concentration was 125 mg/L. The original NaClO process was also optimized, and the best process after optimization was as follows:NaClO dosage was 1.2%, and the reaction time was 30 minutes. When the average influent COD and ammonia nitrogen were 109.7 mg/L and 12.8 mg/L, the average effluent COD and ammonia nitrogen of the catalytic ozone process were 43.5 mg/L and 3.8 mg/L, respectively, and the average removal rates were 60% and 70.4%, respectively; and the average effluent COD and ammonia nitrogen in the NaClO process were 49.8 mg/L and 4.7 mg/L, respectively, and the average removal rates were 54.5% and 63.1%, respectively. Within 30 days, the standard-meeting rate of the catalytic ozonation process effluent was 100%, and that of the NaClO process effluent was 26.7%; the running cost of catalytic ozonation ton water treatment was RMB 1.12/t, and that of the NaClO treatment was RMB 12/t. The catalytic ozonation process was more suitable for treating titanium dioxide wastewater, compared with The NaClO oxidation process.
2021, 39(11): 159-165.
doi: 10.13205/j.hjgc.202111021
Abstract:
In order to enhance the COD removal of petrochemical biochemical effluent, the removal effect of micro flocculation sand filtration and ozone catalytic oxidation on COD in petrochemical biochemical effluent was analyzed. The COD removal under different combination modes of ozone catalytic oxidation tower was compared. The lab-scale, pilot-scale and productive scale of catalytic ozonation were carried out. The ozonation tower with two stages, one-stage aeration and one-stage reflux (reflux ratio 100%) were recommended for its good performance. When the bio-treated petrochemical wastewater was 70~120 mg/L, micro flocculating sand filter effluent was 65~113 mg/L, the remocal rate of COD in two-stage effluent reached 35.0%~42.6%, meeting the emission standard for petroleum chemical industry(GB 31571-2015). Compared with the one stage aeration process production test device, ozone consumption for per unit COD of the selected optimized technology was 1.04 g/g and reduced by 21.2% comparing with the original process (single stage ozonation).
In order to enhance the COD removal of petrochemical biochemical effluent, the removal effect of micro flocculation sand filtration and ozone catalytic oxidation on COD in petrochemical biochemical effluent was analyzed. The COD removal under different combination modes of ozone catalytic oxidation tower was compared. The lab-scale, pilot-scale and productive scale of catalytic ozonation were carried out. The ozonation tower with two stages, one-stage aeration and one-stage reflux (reflux ratio 100%) were recommended for its good performance. When the bio-treated petrochemical wastewater was 70~120 mg/L, micro flocculating sand filter effluent was 65~113 mg/L, the remocal rate of COD in two-stage effluent reached 35.0%~42.6%, meeting the emission standard for petroleum chemical industry(GB 31571-2015). Compared with the one stage aeration process production test device, ozone consumption for per unit COD of the selected optimized technology was 1.04 g/g and reduced by 21.2% comparing with the original process (single stage ozonation).
2021, 39(11): 166-171.
doi: 10.13205/j.hjgc.202111022
Abstract:
As an advanced treatment process, biological activated carbon process can effectively remove organic pollutants from wastewater. In order to investigate the advanced treatment effect of biological activated carbon process on pharmaceutical wastewater, the effect of high-efficiency composite bacteria on wastewater treatment performance of biological activated carbon process was studied, and the influence of the operating parameters was discussed. The results showed that addition of composite bacteria could significantly improve pollutant removal effect. The high-efficiency degradation bacteria coupled with biological activated carbon process had an average removal rate of 38.2% for COD, 77.8% for ammonia nitrogen, and 84.3% for AOX under conditions of packing filling degree of 80% and hydraulic retention time of 10 h. The effluent was superior to the third-level limit value of China's Integrated Wastewater Discharge Standard (GB 8979-1996)。
As an advanced treatment process, biological activated carbon process can effectively remove organic pollutants from wastewater. In order to investigate the advanced treatment effect of biological activated carbon process on pharmaceutical wastewater, the effect of high-efficiency composite bacteria on wastewater treatment performance of biological activated carbon process was studied, and the influence of the operating parameters was discussed. The results showed that addition of composite bacteria could significantly improve pollutant removal effect. The high-efficiency degradation bacteria coupled with biological activated carbon process had an average removal rate of 38.2% for COD, 77.8% for ammonia nitrogen, and 84.3% for AOX under conditions of packing filling degree of 80% and hydraulic retention time of 10 h. The effluent was superior to the third-level limit value of China's Integrated Wastewater Discharge Standard (GB 8979-1996)。
2021, 39(11): 172-178.
doi: 10.13205/j.hjgc.202111023
Abstract:
Taking the groundwater pumping scheme of a chlorinated hydrocarbon-contaminated site as an example, this paper used a numerical model combined algorithm and carried out optimization. The aim of pump-and-treat technology was that carbon tetrachloride concentration of the groundwater was less than 1500 μg/L after continuous extraction for 360 days. The optimization objective function was that the minimum total extraction volume. The simulation and optimization results showed that extraction volume of the initial wells, located in the central axis of the contaminated plume, was better than that of the uniform distribution. We divided the 360 days into two stages, and found that the total extraction volume reduced by 8.3% compared with the constant model. After dividing the 360-day extraction time into four stages, the optimized total extraction volume was reduced by 2.8% compared with the two stages model. However, the pumping rate of the fourth stage was only 274 m3/d. When keeping the total extraction amount stable, increasing the extraction rate of the fourth stage to 814 m3/d could shorten the extraction time to 300 days.
Taking the groundwater pumping scheme of a chlorinated hydrocarbon-contaminated site as an example, this paper used a numerical model combined algorithm and carried out optimization. The aim of pump-and-treat technology was that carbon tetrachloride concentration of the groundwater was less than 1500 μg/L after continuous extraction for 360 days. The optimization objective function was that the minimum total extraction volume. The simulation and optimization results showed that extraction volume of the initial wells, located in the central axis of the contaminated plume, was better than that of the uniform distribution. We divided the 360 days into two stages, and found that the total extraction volume reduced by 8.3% compared with the constant model. After dividing the 360-day extraction time into four stages, the optimized total extraction volume was reduced by 2.8% compared with the two stages model. However, the pumping rate of the fourth stage was only 274 m3/d. When keeping the total extraction amount stable, increasing the extraction rate of the fourth stage to 814 m3/d could shorten the extraction time to 300 days.
